Tag Archives: underground storage

Environment, Rainwater Catchment

Rainwater Collection Meets Seattle Code & Saves Money

The new Seattle 2016 Stormwater and Drainage code is prompting many architects to include detention/infiltration systems into their residential designs to mitigate unwanted roof runoff. This typically incorporates roof runoff to be collected temporarily, in above ground storage, to be slowly released into an infiltration system on site. This can be a series of infiltration ditches or some type of rain garden. During the dry season, the stored water can be used for irrigation. However, a problem with this theory is that storage for this type of system is usually inadequate in volume to accommodate much irrigation during the dry periods. Rule of thumb for irrigation requirements are .623 gallons per square foot of planting area per week, or 1″ of rainfall for the healthy growth of plants. This can add up rather quickly; 1,000 square feet of planting requires 623 gallons per week, 2,500 gallons for 1 month or 7,500 gallons for the typical 3 month dry season.

The outcome of this is that a good deal of money is spent to get rid of a good resource with little benefit –  other than compliance with the code. Cisterns and infiltration designs, engineering and implementation can be costly.

RainBank Rainwater Systems takes a more holistic approach to the stormwater code by using rainwater collection for domestic use. With a smaller amount of storage, rainwater can be collected and used for toilet flushing and laundry facility. Almost half of residential water consumption is for these two purposes. That’s right — 48%, per the American Water Works Association. During the rainy season, demand is met by a continued source replenishing the storage. During the dry season, the storage provides enough water to meet these demands. The cost of this type of system is comparable to the coasts of a detention/infiltration system, while reducing your water bill as much as 48% annually.

Rainwater system storage can be underground, where detention tanks cannot. The visual impact and space requirements are reduced, costs are reduced with a return on investment, environmental impacts are reduced, and conservation of city water is enhanced.

RainBank Rainwater Systems will work with your architect, drainage engineer, and contractor to meet the challenge of drainage requirements for your new residential construction. Our designs and installs have been helping meet these challenges for more than 15 years throughout Washington State. RainBank’s team has the experience to turn the requirement of drainage codes into an asset for the customer and the environment.

Contact us now to turn a potentially costly requirement into a win for your project and for the environment.

Rainwater Catchment, Water Tanks

Considerations for Underground Water Storage Tanks

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Xerxes underground tanksRainBank is experiencing increased interest in underground storage for our Seattle customers, requiring special considerations for underground water storage tanks.

Aesthetics and available space are the most common reasons from these customers. Many are building larger homes on small lots that once had a 1,200 square foot home with a front and back yard. New construction is trending towards a larger footprint, leaving less room for water storage tanks. Slimline tanks allow for less visual impact, but are restrictive on volume. Other residents are remodeling older existing homes that still have yard space available – and are looking for greater amounts of storage.  Below grade storage can be the answer, leaving a yard area that can accept landscaping right over the top of the water tanks.

Here are some things to consider with underground storage.

  • First and foremost – costs. Below grade storage will require excavation and. most likely, exporting much of that soil, which would have to be loaded and trucked off site.
  • Drainage needs to taken in account, with the new City of Seattle stormwater rules preferring infiltration for overflow. Where infiltration is not feasible, connection to the city storm system can be implemented for overflow as long as caution is taken to prevent sewer gases  or back flow from entering the tank.
  • Water tanks need to be properly vented and have a riser to access the tank for periodic cleaning and pump service. The installer must be sure that plumbing will not be compromised with slight settling or shifting of the tank.
  • Below grade tanks tend to be more expensive to meet engineering requirements of underground tanks, and once installed, are considered a confined space and caution must be taken if access is necessary. 

Underground-Tank-Construction3-1038x576For those who understand the considerations of underground storage, you have the luxury of landscaping that is free of visual impact and have different available options in tank sizes, styles, and materials. Tanks can be single or multiple, plastic or fiberglass. Cement tanks can be used for non potable use or lined with a NSF certificate for drinking water.